1. Field of the Invention
The invention relates to tire manufacture, and particularly to curing molds for tire blanks. In particular, it concerns tires for civil engineering vehicles such as those used in mines.
2. Related Art
The document WO 2011/001095 in the names of the applicants discloses a tire blank curing mold comprising upper and lower shells that are slidable towards one another and serve to mold the sidewalls of the blank, together with lateral segments that are radially movable relative to the axis of the mold and serve to mold the tread. When the mold is opened, the upward sliding movement of the plate carrying the lower shell causes the segments to move radially relative to the shell so as to release the blank. For this purpose, each segment is associated with a lever hinged to the segment, connected to the frame of the mold and bearing on a ramp of the plate forming a face orientated towards the axis. The radial sliding movement of the segments facilitates the removal of the tread patterns from the mold.
The manufacture of tires for civil engineering vehicles gives rise to specific problems. This is because these tyres are extremely large. Moreover, in recent models, they comprise a large number of relatively fine and deep grooves on their treads, which may have a complex shape (corrugated or hooked, for example) which make removal from the mold more difficult. It is therefore necessary to provide a mechanism for making the segments retract over a longer path during a sliding movement or a movement similar to a sliding movement.